PAPERS that give an insight into the thought process of one of the 20th-century's greatest thinkers were sold at Sotheby's yesterday. The pile of modest-looking sheets covered in corrections were the annotated proofs, letters and other texts relating to Wittgenstein's most influential work, Tractatus Logico- Philosophicus, his revolutionary study of the function of language.

They made pounds 145,865, against an estimated pounds 45,000 to pounds 55,000. Most of the top lots were bought by Hamish Riley-Smith, a British dealer.

Ludwig Wittgenstein (1889-1951), who was born in Vienna, came to England in 1908 and studied logic with Bertrand Russell at Cambridge, wrote the Tractatus in an Italian prisoner of war camp. Even while on active service with the Austrian army, he was to be found in the trenches contemplating logic and philosophy.

The collection included his heavily-revised copy of the original edition of the Tractatus published in 1921. Wittgenstein was disgusted by the number of inaccuracies. It sold for pounds 41,100 to Mr Riley-Smith.

Among Wittgenstein letters sold yesterday was one to C K Ogden, the Cambridge linguistic psychologist responsible for the Tractatus's English translation. In it, Wittgenstein apologises for not being able to lengthen the Tractatus with supplements: 'As to the shortness of the book I am awfully sorry for it; but what can I do?] If you were to squeeze me out like a lemon you would get nothing more out of me.'

Other letters to Ogden include requests to trace the mother of his best friend, David Pinsent, to whom the Tractatus is dedicated. Wittgenstein eventually wrote to Mrs Pin sent, telling her that her son was 'my first and my only friend'.

In the same sale material from the family of Elizabeth Pigot, Lord Byron's childhood sweetheart, sold for pounds 54,418. A British collector bought Byron's inscribed copy of a book of poems for pounds 8,970, against an estimate of pounds 800, and a lock of Bryon's hair in a locket for pounds 1,725.

Also sold were more than 550 love letters to Lady Megan Lloyd George (1902-66), MP for Anglesey from 1929 and daughter of the Liberal prime minister, David Lloyd George. They fetched pounds 3,910 (estimate, pounds 1,000-pounds 1,500). The sender was the Labour peer Lord Noel Baker.